Fast rise and fall time rf burst amplifier



1967 A. A. GORSKI ETAL 3,339,146

FAST RISE AND FALL TIME RF BURST AMPLIFIER Filed July 29, 1964 I 4 I us1 I5OKV Alexander A. Gorski Joseph S. Wulunos,

INVENTORS.

By M J,

MM w W 6. M

United States Patent Ofifice 3,339,146 Patented Aug. 29, 1967 3,339,146FAST RISE AND FALL TIME RF BURST AMPLIFIER Alexander A. Gorski,River-ton, N.J., and Joseph S.

Walunas, Philadelphia, Pa., assignors, by mesne assignments, to theUnited States of America as represented by the Secretary of the ArmyFiled July 29, 1964, Ser. No. 386,100 12 Claims. (Cl. 328-232) ABSTRACTOF THE DISCLOSURE First and second triodes connected to a load such asthe modulating anode of a klystron. Feed-back transformers connected tothe grids of the triodes to provide fast turn on rates. The first triodeis connected in series with the load, is in an on state during RF burstinputs, and is in anoif state when there is no input. The second triodeis connected in parallel to the load, is in an off state during RF burstinputs, and is in an on state when there is no input.

There is present in radar systems a need for providing a dependablesystem for pulsing the modulating anode of a klystron positive withrespect to the cathode. This must be done so as to have the :fullvoltage swing with rise and fall times (in the order of 4 microseconds)with a Wide range of pulse widths to 500 microseconds). A practicaldevice is needed to drive high resistance loads shunted by relativelylarge capacitance with no ringing or droo-p.

It is therefore an object of this invention to provide a pulsing systemsuitable for use in radar systems.

Another object of the present invention is to provide a dependablesystem for pulsing the modulating anode of a kylstron.

These and other objects and advantages of the present invention willbecome apparent from the following detailed description and from theaccompanying drawing, in which the single figure is a schematic circuitdiagram according to the invention.

A RF burst (from a source not shown) of signal voltages is fed toterminals 1 and 2. Terminals 1 and 2 are connected across primarywinding 5 of transformer 4 and across primary winding 3 of transformer6. (Capacitor is used to resonate secondary winding 8 at RF.) Thevoltage across center tapped secondary winding 8 is rectified byrectifiers 11 and 12. Capacitor 14 is connected in circuit to provideproper filtering action. The output of the rectifiers is applied toterminals 21 and 22.

Control element 24 is a vacuum tube having input and output circuitswhich have sides defined by circuit connections to the tubes anode 26,grid 27 and cathode 28. Anode 26 is connected directly to ground. Grid27 is connected to terminal 21. Cathode 28 of tube 24 is connected toprimary winding 30 of transformer 31. Secondary winding 32 oftransformer 31 is connected in parallel with a rectifier 34. A seriescircuit comprising rectifier 36, the parallel combination of winding 32and rectifier 34, and resistor 38 is connected across terminals 21 and22. A capacitor 40 is connected to one side of winding 30 and to ajunction between resistor 38 and secondary winding 32. A source of biasvoltage 42 is connected to said one side of winding 30 and terminal 22.A voltage divider 44 having a slider arm is connected across battery 42.

A triode 50 having anode 51, grid 52 and cathode 53 has its cathodeconnected to a junction 55. The grid of tube 50 is connected to sliderarm 46 of voltage divider 44.

Secondary winding 61 of isolating transformer 6 is connected to an inputcircuit of a triode 62 by way of diode 109. A resistor 63 is connectedacross cathode of diode 109 and junction 110. Battery 68 connects theoutput circuit of tube 62 to terminals 70 and 71.

Control element is a vacuum tube having input and output circuits whichhave sides defined by circuit connections to the tubes anode 81, grid 82and cathode 83. Tube 80 is shown having its anode 81 connected tojunction 55, its grid 82 connected to terminal 70, and its cathode 83connected to one side of primary winding 78 of transformer 76. Secondarywinding 75 of transformer 76 is connected to terminals 70 and 71 by wayof capacitor 74. A battery is connected to terminals 70 and 71 by Way ofresistor 91. Resistor 92 is connected between junction 55 and junction56. Junction 56 is connected to output terminal 93.

Output terminals 93 and 94 may have a high resistance load 98 shunted bya relatively large capacitance 96. The voltage across output terminals93 and 94 may also be supplied to a modulating anode 101 and cathode 103circuit of a kylstron 105 either with or without the load elements 96and 98. The kylstron has anode element 106 and has a collector element108 connected to a ground circuit. A 150 kv. D.C. source 114 havingoutput terminals 115 and 116 is connected between output terminal 94 andground to provide power for the system and the klystron.

The invention performs in the following manner. A RF burst of apredetermined pulse width (variable over a wide range) is fedsimultaneously to primaries 3 and 5 of isolating transformers 4 and 6.

The RF burst is rectified on the secondary side of transformer 4 byrectifiers 11 and 12. This full wave rectified pulse triggers tube 24,and due to the regenerative action of the blocking oscillatortransformer 31, a high positive voltage spike is placed on the grid oftube 24. The voltage level of the spike and pulse Width of the spike iscontrolled by the design of the transformer 31. This voltage spike willenable the tube 24 to act as a high current source and produce a rapidrise time (on the order of 4 microseconds) for a kv. travel. After thisinitial 4 microseconds spike, caused by transformer 31, the input pulsetakes over and the level of the input pulse determines whether there isa rising, falling or a preferably flat pulse fed to the Mod-Anodecircuit of the klystron.

Tube 80 is normally conducting, however, when tube 62 is fired by theinput pulse, battery 68 Will apply a reverse bias to the grid 82 of tube80; therefore cutting off tube 80. At the trailing edge of the inputpulse, tube 62 starts to cut off and the voltage level of anode 66 willstart rising, finally triggering tube 80 to a conducting condition.Transformer 76 serves a similar blocking oscillator function astransformer 31.

Tube 80 now conducts heavily causing a voltage to develop acrossresistor 92 which triggers tube 50. Tube 50 will now discharge the gridof tube 24; therefore cutting tube 24 off in a very short time. Thiswill result in a rapid discharge of the Mod-Anode of the klystron;therefore yielding extremely fast fall times.

While the invention has been described with reference to a preferredembodiment thereof, it will be apparent that various modifications andother embodiments thereof will occur to those skilled in the art withinthe scope of the invention. Accordingly, we desire the scope of ourinvention to be limited only by the appended claims.

We claim:

1. In combination first and second control elements having input andoutput circuits; a source of signal voltages connected to the inputcircuits of said first and second control elements by first and secondcircuit means respectrvely; a source of DC supply voltage having firstand second output terminals, wherein said first output terminal isconnected to one side of said output circuit of the first controlelement by way of a third circuit means; a load circuit having first andsecond load terminals; fourth circuit means connecting another'side ofthe output circuit of said first control element to the first loadterminal; fifth circuit means connecting one side of the output circuitof said second control element to said first load terminal; said firstterminal of said source of DC supply voltage being connected to thesecond load terminal; and means connecting another side of the outputcircuit of the second control element to said second output terminal ofthe source of DC voltage.

2. A device as set forth in claim 1, wherein said fourth circuit meansis a resistor.

3. A device as set forth in claim 2, wherein said fifth circuit means isthe primary winding of a transformer; said transformer having asecondary winding connected across the input circuit of the secondcontrol element.

4. A device as set forth in claim 3 further comprising a third controlelement having an output circuit connected across the input circuit ofsaid second control element and an input circuit connected across saidresistor.

5. A device as set forth in claim 4, wherein said first, second andthird control elements are triodes.

6. A device as set forth in claim 5, wherein said third circuit means isthe primary winding of a transformer; said transformer having asecondary winding connected across the input circuit of the firstcontrol element.

7. A device as set forth in claim 6, wherein said second circuit meansis a full wave rectifier.

8. A device as set forth in claim 7, wherein said first circuit means isan amplifier.

9. A device as set forth in claim 8, wherein said load circuit is amodulating anode and cathode circuit of a klystron.

10. A pulser comprising first triode means having first anode, cathodeand grid elements; a source of signal voltages connected across saidfirst grid and cathode elements; a resistor; a second triode meanshaving second anode, cathode and grid elements; means connecting saidsignal voltages across the second cathode and grid elements; a seriescircuit comprising the second cathode and anode of said second triodemeans, the resistor, said first cathode and said first anode; a sourceof DC power having positive and negative terminals; a load circuithaving first and second load terminals; connections between the negativeterminal, the first load terminal and the cathode of the second triodemeans; means connecting the positive terminal of the source of power tothe anode of the first triode; and connection means connecting thesecond load terminal to a junction between the resistor and said firstcathode.

11. A pulser as set forth in claim 10 further comprising a third triodemeans having third anode, cathode and grid elements; said third anodebeing connected to the first grid of the first triode means; said thirdcathode being connected to said second anode of the second triode means;and said third grid being connected to said second load terminal.

12. A pulser as set forth in claim 11 further comprising a klystronhaving a modulating anode and a cathode; said load circuit comprisingthe modulating anode connected to the second load terminal and thecathode connected to the first load terminal.

References Cited UNITED STATES PATENTS 2,948,855 8/ 1960 Swanson et a1328-67 3,098,980 7/1963 Dodington 3327 3,167,717 1/l965 Jones et a1.328-61 3,257,619 6/1966 Fackler et a1. 328-65 JAMES W. LAWRENCE, PrimaryExaminer.

V. LAFRANCHI, Assistant Examiner.

1. IN COMBINATION FIRST AND SECOND CONTROL ELEMENTS HAVING INPUT ANDOUTPUT CIRCUITS; A SOURCE OF SIGNAL VOLTAGES CONNTECTED TO THE INPUTCIRCUITS OF SAID FIRST AND SECOND CONTROL ELEMENTS BY FIRST AND SECONDCIRCUIT MEANS RESPECTIVELY; A SOURCE OF DC SUPPLY VOLTAGE HAVING FIRSTAND SECOND OUTPUT TERMINALS, WHEREIN SAID FIRST OUTPUT TERMINAL ISCONNECTED TO ONE SIDE OF SAID OUTPUT CIRCUIT OF THE FIRST CONTROLELEMENT BY WAY OF A THIRD CIRCUIT MEANS; A LOAD CIRCUIT HAVING A FIRSTAND SECOND LOAD TERMINALS; FOURTH CIRCUIT MEANS CONNECTING ANOTHER SIDEOF THE OUTPUT CIRCUIT OF SAID FIRST CONTROL ELEMENT TO THE FIRST LOADTERMINAL; FIFTH CIRCUIT MEANS CONNECTING ONE SIDE OF THE OUTPUT CIRCUITOF SAID SECOND CONTROL ELEMENT TO SAID FIRST LOAD TERMINAL; SAID FIRSTTERMINAL OF SAID SOURCE OF DC SUPPLY VOLTAGE BEING CONNECTED TO THESECOND LOAD TERMINAL; AND MEANS CONNECTING ANOTHER SIDE OF THE OUTPUTCIRCUIT OF THE SECOND CONTROL ELEMENT TO SAID SECOND OUTPUT TERMINAL OFTHE SOURCE OF DC VOLTAGE.